The invention relates to an apparatus for fixing a roll ring on a roll shaft, said roll shaft being rotatably mounted in two roll stands by means of shaft bearings on either side of said roll ring.
In a known apparatus of this type (EP-A2 163 104) with an axially tensionable conical sleeve a radial pretension is to be produced in the roll ring made from hard metal and disposed on the conical roll shaft. The pretensioning force is applied with a nut screwed onto the threaded portion on the shaft stump. This pretension is necessary for centering the roll ring and ensuring adequate force locking for the torque transmission from the roll shaft to the roll ring.
Because of the tension sensitivity of hard metal roll rings, exceeding the admissible roll ring pretension can lead directly to increasing the danger of breakage. However, tensioning within the range of the admissible limit values must be aimed at to ensure reliable rotary entrainment even under shock load.
The known axial adjustment of the conical sleeve with the pretensioning nut does not permit an adequate accuracy of the pretensioning of the roll ring because this conical sleeve bearing over its entire length conically on the roll shaft must also carry and centre a roll shaft bearing and it is thus completely unclear where the tightening moment actually acts.
Furthermore, AT-PS 313,839 discloses an apparatus for fixing a roll ring, although with a flying arrangement of the roll ring, the free end of the roll shaft bearing an end cap with an external thread for receiving a pretensioning nut with the aid of which the roll ring consisting of hard metal and provided with a corresponding roll pass for making profile wires is subjected to an axial compressive pretension between two thrust rings. In addition to this axial compressive pretension a radial pretension is desired, this being done with the aid of a conical sleeve between the roll ring and the roll shaft conical in the region of the roll ring. Said conical sleeve is driven into the annular gap between the roll ring and the conical part of the roll shaft via adjusting screws held screwably adjustable in the end cap and distributed over the periphery. This pretensioning of the roll ring serves firstly to ensure adequate force locking for the torque transmission from the roll shaft to the roll ring and secondly reduces the notch effects and loads occurring in the region of the roll ring in the rolling operation. Since due to the tension sensitivity of the hard metal roll rings exceeding the admissible ring pretensioning leads directly to an increase in the danger of breakage, but nevertheless a pretensioning of the roll rings in the range of the admissible limit value is desired to ensure rotary entraining of the roll rings even under shock load, an exact adjustment of the pretension both in the axial and radial direction is necessary, advantageously independently of each other.
The known axial adjustment of the conical sleeve via adjusting screws held screwably adjustable in the end cap admittedly permits a setting of the radial pretension independent of the axial pretension but this setting is complicated because the individual adjusting screws must be tightened with a torque key. In addition, this construction does not provide any indication how in a mounting of the roll shaft on both sides of the roll ring the thrust transmitting means would have to be formed to achieve satisfactory mounting of the roll shaft in the roll stand and satisfactory pretensioning of the roll ring.